Deep learning for automated left ventricular outflow tract diameter measurements in 2D echocardiography.

BACKGROUND: Measurement of the left ventricular outflow tract diameter (LVOTd) in echocardiography is a common source of error when used to calculate the stroke volume. The aim of this study is to assess whether a deep learning (DL) model, trained on a clinical echocardiographic dataset, can perform automatic LVOTd measurements on par with expert cardiologists. METHODS: Data consisted of 649 consecutive transthoracic echocardiographic examinations of patients with coronary artery disease admitted to a university hospital. 1304 LVOTd measurements in the parasternal long axis (PLAX) and zoomed parasternal long axis views (ZPLAX) were collected, with each patient having 1-6 measurements per examination. Data quality control was performed by an expert cardiologist, and spatial geometry data was preserved for each LVOTd measurement to convert DL predictions into metric units. A convolutional neural network based on the U-Net was used as the DL model. RESULTS: The mean absolute LVOTd error was 1.04 (95% confidence interval [CI] 0.90-1.19) mm for DL predictions on the test set. The mean relative LVOTd errors across all data subgroups ranged from 3.8 to 5.1% for the test set. Generally, the DL model had superior performance on the ZPLAX view compared to the PLAX view. DL model precision for patients with repeated LVOTd measurements had a mean coefficient of variation of 2.2 (95% CI 1.6-2.7) %, which was comparable to the clinicians for the test set. CONCLUSION: DL for automatic LVOTd measurements in PLAX and ZPLAX views is feasible when trained on a limited clinical dataset. While the DL predicted LVOTd measurements were within the expected range of clinical inter-observer variability, the robustness of the DL model requires validation on independent datasets. Future experiments using temporal information and anatomical constraints could improve valvular identification and reduce outliers, which are challenges that must be addressed before clinical utilization.

Imaging and heart failure: myocardial strain.

PURPOSE OF REVIEW: To summarize literature on the application of myocardial strain in patients with heart failure published since 2018. RECENT FINDINGS: Left ventricular (LV) and right ventricular strain provides important prognostic information in patients with acute and chronic heart failure and new insights in disease mechanisms in amyloidosis. The addition of left atrial strain to current societal diastolic dysfunction criteria may improve detection of clinically relevant diastolic dysfunction. The recently developed method for noninvasive estimation of myocardial work incorporates loading conditions into the evaluation of LV performance that may be important for selection of patients for cardiac resynchronization therapy. SUMMARY: Evidence linking myocardial strain to adverse outcomes in heart failure is steadily being developed. Although GLS seems to be ready for clinical use, further validation and standardization of RV, LA strain and myocardial work is needed.

No adverse association between exercise exposure and diffuse myocardial fibrosis in male endurance athletes.

The potential association between endurance exercise and myocardial fibrosis is controversial. Data on exercise exposure and diffuse myocardial fibrosis in endurance athletes are scarce and conflicting. We aimed to investigate the association between exercise exposure and markers of diffuse myocardial fibrosis by cardiovascular magnetic resonance imaging (CMR) in endurance athletes. We examined 27 healthy adult male competitive endurance athletes aged 41 ± 9 years and 16 healthy controls in a cross sectional study using 3 Tesla CMR including late gadolinium enhancement and T1 mapping. Athletes reported detailed exercise history from 12 years of age. Left ventricular total mass, cellular mass and extracellular mass were higher in athletes than controls (86 vs. 58 g/m2, 67 vs. 44 g/m2 and 19 vs. 13 g/m2, all p < 0.01). Extracellular volume (ECV) was lower (21.5% vs. 23.8%, p = 0.03) and native T1 time was shorter (1214 ms vs. 1268 ms, p < 0.01) in the athletes. Increasing exercise dose was independently associated with shorter native T1 time (regression coefficient - 24.1, p < 0.05), but expressed no association with ECV. Our results indicate that diffuse myocardial fibrosis has a low prevalence in healthy male endurance athletes and do not indicate an adverse dose-response relationship between exercise and diffuse myocardial fibrosis in healthy athletes.

Mortality in Patients with Acute Coronary Syndrome-A Prospective 5-Year Follow-Up Study.

Our objective was to compare long-term outcomes in patients with non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) between two time periods in Southern Norway. There are limited contemporary data comparing long-term follow-up after revascularization in the last decades. This prospective follow-up study consecutively included both NSTEMI and STEMI patients during two time periods, 2014-2015 and 2004-2009. Patients were followed up for a period of 5 years. The primary outcome was all-cause mortality after 1 and 5 years. A total of 539 patients with acute myocardial infarction (AMI), 316 with NSTEMI (234 included in 2014 and 82 included in 2007) and 223 with STEMI (160 included in 2014 and 63 included in 2004). Mortality after NSTEMI was high and remained unchanged during the two time periods (mortality rate at 1 year: 3.5% versus 4.9%, p = 0.50; and 5 years: 11.4% versus 14.6%, p = 0.40). Among STEMI patients, all-cause mortality at 1 year was reduced in 2014 compared to 2004 (1.3% versus 11.1%, p < 0.001; and 5 years: 7.0% versus 22.2%, p = 0.004, respectively). Time to coronary angiography in NSTEMI patients remained unchanged between 2014 and 2007 (28.2 h [IQR 18.1-46.3] versus 30.3 h [IQR 18.0-48.3], p = 0.20), while time to coronary angiography in STEMI patients was improved in 2014 compared with 2004 (2.8 h [IQR 2.0-4.8] versus 21.7 h [IQR 5.4-27.1], p < 0.001), respectively. During one decade of AMI treatment, mortality in patients with NSTEMI remained unchanged while mortality in STEMI patients decreased, both at 1 and 5 years.

Myocardial inefficiency is an early indicator of exercise-induced myocardial fatigue.

Background: The effect of prolonged, high-intensity endurance exercise on myocardial function is unclear. This study aimed to determine the left ventricular (LV) response to increased exercise duration and intensity using novel echocardiographic tools to assess myocardial work and fatigue. Materials and methods: LV function was assessed by echocardiography before, immediately, and 24 h after a cardiopulmonary exercise test (CPET) and a 91-km mountain bike leisure race. Cardiac Troponin I (cTnI) was used to assess myocyte stress. Results: 59 healthy recreational athletes, 52 (43-59) years of age, 73% males, were included. The race was longer and of higher intensity generating higher cTnI levels compared with the CPET (p < 0.0001): Race/CPET: exercise duration: 230 (210, 245)/43 (40, 45) minutes, mean heart rate: 154 ± 10/132 ± 12 bpm, max cTnI: 77 (37, 128)/12 (7, 23) ng/L. Stroke volume and cardiac output were higher after the race than CPET (p < 0.005). The two exercises did not differ in post-exercise changes in LV ejection fraction (LVEF) or global longitudinal strain (GLS). There was an increase in global wasted work (p = 0.001) following the race and a persistent reduction in global constructive work 24 h after exercise (p = 0.003). Conclusion: Increased exercise intensity and duration were associated with increased myocardial wasted work post-exercise, without alterations in LVEF and GLS from baseline values. These findings suggest that markers of myocardial inefficiency may precede reduction in global LV function as markers of myocardial fatigue.

Strain echocardiography improves prediction of arrhythmic events in ischemic and non-ischemic dilated cardiomyopathy.

BACKGROUND: Recent evidence suggests that an implantable cardioverter defibrillator (ICD) in non-ischemic cardiomyopathy (NICM) may not offer mortality benefit. We aimed to investigate if etiology of heart failure and strain echocardiography can improve risk stratification of life threatening ventricular arrhythmia (VA) in heart failure patients. METHODS: This prospective multi-center follow-up study consecutively included NICM and ischemic cardiomyopathy (ICM) patients with left ventricular ejection fraction (LVEF) <40%. We assessed LVEF, global longitudinal strain (GLS) and mechanical dispersion (MD) by echocardiography. Ventricular arrhythmia was defined as sustained ventricular tachycardia, sudden cardiac death or appropriate shock from an ICD. RESULTS: We included 290 patients (67 ± 13 years old, 74% males, 207(71%) ICM). During 22 ± 12 months follow up, VA occurred in 32(11%) patients. MD and GLS were both markers of VA in patients with ICM and NICM, whereas LVEF was not (p = 0.14). MD independently predicted VA (HR: 1.19; 95% CI 1.08-1.32, p = 0.001), with excellent arrhythmia free survival in patients with MD <70 ms (Log rank p < 0.001). Patients with NICM and MD <70 ms had the lowest VA incidence with an event rate of 3%/year, while patients with ICM and MD >70 ms had highest VA incidence with an event rate of 16%/year. CONCLUSION: Patients with NICM and normal MD had low arrhythmic event rate, comparable to the general population. Patients with ICM and MD >70 ms had the highest risk of VA. Combining heart failure etiology and strain echocardiography may classify heart failure patients in low, intermediate and high risk of VA and thereby aid ICD decision strategies.

Impact of transcatheter aortic valve implantation on mechanical dispersion.

Objectives: The physiological determinants of left ventricular (LV) mechanical dispersion (MD) are not fully explored. We aimed to investigate the impact of afterload reduction and changes in ventricular conduction on LV MD after transcatheter aortic valve implantation (TAVI). Methods: Patients with severe aortic stenosis (AS) were examined in a prospective, repeated measures observational cohort study before and after an uncomplicated transfemoral TAVI in a single tertiary centre. LV MD was assessed by speckle tracking echocardiography. Valvulo-arterial impedance (ZVA) was used as a measure of global afterload. Results: We included 140 consecutive patients (83±8 years old, 49% women, logistic EuroSCORE 16±10) with severe AS (valve area 0.7±0.2 cm2, mean transvalvular gradient 54±18 mm Hg) and a relatively preserved LV ejection fraction (52%±11%). After TAVI, we observed favourable changes in transvalvular gradients and ZVA in all patients. Compared with baseline, postprocedural MD was significantly lower in 108 patients with unchanged ventricular conduction (55±17 ms vs 51±17 ms, p=0.02) and higher in 28 patients with TAVI-induced left bundle branch block (51±13 ms vs 62±19 ms, p≤0.001). During 22±9 months observation, 22 patients died. Postprocedural MD was associated with mortality in a univariate Cox regression model (HR=1.24 (1.01-1.52), p<0.04, per 10 ms increase). Conclusions: Isolated afterload reduction was associated with reduction of MD, while concomitant impairment of ventricular conduction resulted in a more pronounced MD after TAVI, indicating that loading conditions and conduction should be considered when evaluating MD. A pronounced postprocedural LV MD was associated with mortality.

Echocardiographic assessment of left ventricular systolic function.

Left ventricular (LV) ejection fraction (LVEF) is the most validated and commonly used echocardiographic measure of systolic function. LVEF has a unique position in cardiology having severed as selection criteria for therapeutic trials that constitute the evidence base of today's treatment recommendations. Assessment of LV systolic function by global longitudinal strain (GLS) from speckle tracking echocardiography (STE) is a sensitive and feasible method that overcomes many of the limitations of LVEF, including reproducibility issues of serial testing and detection of LV dysfunction in pathologically remodeled hearts. This review discusses the role of STE as a complementary method to LVEF in estimation of LV systolic function.

Classical mechanical dyssynchrony is rare in transcatheter aortic valve implantation-induced left bundle branch block.

AIMS: Left bundle branch block (LBBB) is a frequent conduction abnormality after transcatheter aortic valve implantation (TAVI). We aimed to investigate how TAVI procedure related conduction abnormalities influence ventricular mechanics and prognosis, with particular focus on new-onset persistent LBBB. METHODS AND RESULTS: A total of 140 consecutive patients with severe aortic stenosis (83 ± 8 years old, 49% women) undergoing TAVI in a single tertiary centre were included in a repeated measures study. Changes in myocardial function and contraction patterns were investigated in relation to changes in electrical conduction and afterload by speckle tracking echocardiography. Whether patients with new-onset LBBB acquired classical dyssynchronous contractions was assessed by longitudinal strain in apical four-chamber view. Global longitudinal strain improvement was seen in all patients (-15.1 ± 4.3 vs. -16.1 ± 3.9%, P < 0.01, n = 140), and all subgroups, regardless of pre-existing or procedure-acquired conduction abnormalities immediately after TAVI. New-onset LBBB fulfilling strict electrocardiogram (ECG) criteria was observed in 28 patients (20%). The vast majority of new-onset LBBB patients (n = 26, 93%) had homogenous contractions. Classical dyssynchronous LBBB contractions were only observed in 2 patients (7%) with new-onset LBBB. Patients with new-onset LBBB and patients without acquired conduction disorders had similar mortality rates during 19 ± 9 months of follow-up [11.1, 95% confidence interval (CI) 4.6-26.8 vs. 8.1, 95% CI 4.8-13.7 per 100 patients years, P = 0.53]. CONCLUSION: Classical dyssynchronous LBBB contractions were absent in most patients with new-onset post-TAVI LBBB, even when applying strict ECG criteria. Patients with and without new-onset LBBB experienced similar prognosis with regards to mortality.

Circulating secretoneurin concentrations in patients with moderate to severe aortic stenosis.

BACKGROUND: Secretoneurin (SN) concentrations provide important prognostic information in patients with myocardial dysfunction. Whether preoperative SN concentrations improve risk assessment in patients with moderate to severe aortic stenosis (AS) is unknown. METHODS: We included 57 patients with moderate to severe AS referred for presurgical evaluation. All patients were examined with comprehensive echocardiography, electrocardiogram (ECG), and biochemical measurements and compared to 10 age- and sex-matched healthy subjects. RESULTS: Median (quartile 1-3) SN concentrations were 141 (121-163) pmol/L in AS patients and 132 (106-148) pmol/L in control subjects (p = .17). Lower estimated creatinine clearance and use of diuretics, but not standard ECG or echocardiographic indices and cardiac biomarkers, were associated with increasing SN concentrations. Fifteen patients (26%) died during 3.5 years median follow-up. SN concentrations were higher in non-survivors than survivors: 156 (133-209) vs. 140 (116-155) pmol/L, p = .007. Higher SN concentrations were associated with increased risk of mortality also after adjustment for established risk indices, biomarkers, and status regarding valvular surgery: hazard ratio per lnSN 15.13 (95% CI 1.05-219.00); p = .046. Receiver operating characteristics area under the curve for SN to predict mortality was 0.74 (95% CI 0.60-0.88) compared to 0.73 (0.59-0.87) for high-sensitivity cardiac troponin T and 0.67 (0.51-0.82) for N-terminal pro-B-type natriuretic peptide. The previously identified cut-off of SN >204 pmol/L in cardiac surgical patients predicted mortality also in this cohort. CONCLUSIONS: SN concentrations improve risk assessment in patients with moderate to severe AS by providing additional prognostic information to established risk indices such as echocardiography, ECG, and established cardiac biomarkers.

Prognostic Value of Left Ventricular Deformation Parameters in Patients with Severe Aortic Stenosis: A Pilot Study of the Usefulness of Strain Echocardiography.

BACKGROUND: In patients with aortic stenosis, subtle alterations in myocardial mechanics can be detected by speckle-tracking echocardiography before reduction of left ventricular ejection fraction (LVEF). METHODS: In this prospective study, 162 patients with aortic stenosis with an average aortic valve area of 0.7 ± 0.2 cm2 and a mean LVEF of 60 ± 11% were included. Global longitudinal strain (GLS) and mechanical dispersion (SD of time from Q/R on the electrocardiogram to peak strain in 16 left ventricular segments) were assessed using echocardiography, and all-cause mortality (n = 37) was recorded during 37 ± 13 months of follow-up. RESULTS: Overall, nonsurvivors had more pronounced mechanical dispersion and worse GLS compared with survivors (74 ± 24 vs 61 ± 18 msec [P < .01] and -14.5 ± 4.4% vs -16.7 ± 3.6% [P < .01], respectively). In the 42 conservatively treated patients without surgical aortic valve replacement, a similar pattern was observed in nonsurvivors versus survivors (mechanical dispersion, 80 ± 24 vs 57 ± 14 msec [P < .01]; GLS, -14.0 ± 4.9% vs -17.1 ± 3.8% [P = .04], respectively). Mechanical dispersion was significantly associated with mortality (hazard ratio per 10-msec increase, 1.23; 95% CI, 1.07-1.42; P < .01) in a Cox model adjusted for LVEF and with aortic valve replacement treatment as a time-dependent covariate. Continuous net reclassification improvement showed that mechanical dispersion was incremental to LVEF, GLS, and valvulo-arterial impedance when adjusting for aortic valve replacement treatment in the total population. CONCLUSION: Increased mechanical dispersion may be a risk marker providing novel prognostic information in patients with aortic stenosis.

Mitral valve analysis using a novel 3D holographic display: a feasibility study of 3D ultrasound data converted to a holographic screen.

The aim of the present study was to test the feasibility of analyzing 3D ultrasound data on a novel holographic display. An increasing number of mini-invasive procedures for mitral valve repair require more effective visualization to improve patient safety and speed of procedures. A novel 3D holographic display has been developed and may have the potential to guide interventional cardiac procedures in the near future. Forty patients with degenerative mitral valve disease were analyzed. All had complete 2D transthoracic (TTE) and transoesophageal (TEE) echocardiographic examinations. In addition, 3D TTE of the mitral valve was obtained and recordings were converted from the echo machine to the holographic screen. Visual inspection of the mitral valve during surgery or TEE served as the gold standard. 240 segments were analyzed by 2 independent observers. A total of 53 segments were prolapsing. The majority included P2 (31), the remaining located at A2 (8), A3 (6), P3 (5), P1 (2) and A1 (1). The sensitivity and specificity of the 3D display was 87 and 99 %, respectively (observer I), and for observer II 85 and 97 %, respectively. The accuracies and precisions were 96.7 and 97.9 %, respectively, (observer I), 94.3 and 88.2 % (observer II), and inter-observer agreement was 0.954 with Cohen's Kappa 0.86. We were able to convert 3D ultrasound data to the holographic display. A very high accuracy and precision was shown, demonstrating the feasibility of analyzing 3D echo of the mitral valve on the holographic screen.